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<a name="Advanced-distributed_002dtranspose-interface"></a>
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Next: <a href="An-improved-replacement-for-MPI_005fAlltoall.html#An-improved-replacement-for-MPI_005fAlltoall" accesskey="n" rel="next">An improved replacement for MPI_Alltoall</a>, Previous: <a href="Basic-distributed_002dtranspose-interface.html#Basic-distributed_002dtranspose-interface" accesskey="p" rel="prev">Basic distributed-transpose interface</a>, Up: <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" accesskey="u" rel="up">FFTW MPI Transposes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Advanced-distributed_002dtranspose-interface-1"></a>
<h4 class="subsection">6.7.2 Advanced distributed-transpose interface</h4>

<p>The above routines are for a transpose of a matrix of numbers (of type
<code>double</code>), using FFTW&rsquo;s default block sizes.  More generally, one
can perform transposes of <em>tuples</em> of numbers, with
user-specified block sizes for the input and output:
</p>
<div class="example">
<pre class="example">fftw_plan fftw_mpi_plan_many_transpose
                (ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t howmany,
                 ptrdiff_t block0, ptrdiff_t block1,
                 double *in, double *out, MPI_Comm comm, unsigned flags);
</pre></div>
<a name="index-fftw_005fmpi_005fplan_005fmany_005ftranspose"></a>

<p>In this case, one is transposing an <code>n0</code> by <code>n1</code> matrix of
<code>howmany</code>-tuples (e.g. <code>howmany = 2</code> for complex numbers).
The input is distributed along the <code>n0</code> dimension with block size
<code>block0</code>, and the <code>n1</code> by <code>n0</code> output is distributed
along the <code>n1</code> dimension with block size <code>block1</code>.  If
<code>FFTW_MPI_DEFAULT_BLOCK</code> (0) is passed for a block size then FFTW
uses its default block size.  To get the local size of the data on
each process, you should then call <code>fftw_mpi_local_size_many_transposed</code>.
<a name="index-FFTW_005fMPI_005fDEFAULT_005fBLOCK-1"></a>
<a name="index-fftw_005fmpi_005flocal_005fsize_005fmany_005ftransposed"></a>
</p>



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